Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

typedef pair<int,int> P;

const int INF=1e9;
int h,w;
char maze[51][51];
int dx[]={1,-1,0,0},dy[]={0,0,1,-1};
int d[50][50];

int main(){
  cin>>h>>w;
  for(int i=0;i<h;++i)cin>>maze[i];

  int ans=h*w;

  for(int i=0;i<h;++i)
    for(int j=0;j<w;++j)
        ans-=maze[i][j]=='#';

  for(int i=0;i<h;++i)
    for(int j=0;j<w;++j)
      d[i][j]=INF;

  queue<P> que;

  que.push(P(0,0));
  d[0][0]=1;

  while(que.size()){

    P p=que.front();
    que.pop();

    if(p.first==h-1&&p.second==w-1)
        break;

    for(int i=0;i<4;++i){

        int x=p.first+dx[i], y=p.second+dy[i];

        if(0<=x && x<h && 0<=y && y<w && maze[x][y]!='#' && d[x][y]==INF){
            que.push(P(x,y));
            d[x][y]=d[p.first][p.second]+1;
        }

    }

  }

  cout << (d[h-1][w-1]==INF? -1:ans-d[h-1][w-1]) << endl;

  return 0;
}